硅对水稻土磷吸附-解吸行为的影响

Adsorption-Desorption Behaviors of Phosphorus under Different Silicon Concentrations in Paddy Soils

硅、磷两种元素都是对作物生长十分重要的元素，两者之间的相互作用影响它们的生物有效性。以浙江上虞的水稻土为研究对象，研究了不同硅添加水平下，水稻土对磷的吸附与解吸行为。研究结果表明，土壤中加硅显著降低了土壤对P的吸附量，且加硅量越大，土壤对磷的吸附量越小。Freundlich和线性方程都能很好的拟合土壤对磷的吸附等温线，且相关系数都达到极显著相关。土壤加硅使Freundlich常数K显著减少，表明加硅减少了土壤对磷的吸附能力。土壤加硅显著增加了土壤磷的解吸量（P〈0．05），当土壤添加Si100mgkg^-1和200mgkg^-1时，土壤解吸量分别比对照增加了1．42％。58．9％和26．2％～196．8％。通过磷的吸附一解吸动力学可知，随着吸附时间的延长，土壤对磷的吸附量和解吸量呈现出先快速增加而后平稳的趋势。土壤加硅减少了土壤对磷的吸附速率而增加了土壤对磷的解吸速率。土壤对磷的吸附动力学可用双常数方程和Elovich方程进行拟合（P〈0．001或P〈0．01）。本研究结果表明，土壤加硅减少了土壤磷的吸附并增加了土壤磷的解吸，从而增大了土壤磷的活性和生物有效性。

Silicon （Si） and phosphorus （P） are very important elements for the growth of crops. The interactions between them have great effects on their bioavailability. In this paper, effect of Si on adsorption and desorption behaviors of P was studied in paddy soil from ShangYu, Zhejiang Province. The results showed that addition of Si into the soil decreased the amount of adsorption of P. The amount of adsorption of P decreased with the increase of Si concentration in soils. The isotherm of P could be well described by Freundlich and liner equation （P〈0.001） for any Si treatments. K value in Freundlich equation decreased when Si were added into soil, which indicated that Si decreased adsorption capacity of P in soil. Addition of Si into soil increased amounts of desorption of P in soil. The amounts of adsorption and desorption of P increased rapidly at first phase of adsorption-desorption and then increased slowly and maintain steady. The addition of Si into soil reduced the adsorption rate of P and increased the desorption rate of P. It can be known from the present study that addition of Si into soil increases the mobilization and bioavailability of P.